\begin{table}%t1
\caption[GLMP objects in common with the "Arecibo
sample'']{\label{tab_ext:common_obj}Objects in common to the GLMP
catalogue and to the "Arecibo sample''.}
%\centering
\par
\begin{tabular}[t]{cccc}
\hline\hline\noalign{\smallskip}
GLMP & IRAS & GLMP & IRAS \\
\noalign{\smallskip}\hline\noalign{\smallskip}
842 & 18517+0037 & 851 & 18549+0208 \\
876 & 19065+0832 & 877 & 19067+0811 \\
882 & 19081+0322 & 901 & 19183+1148 \\
902 & 19188+1057 & 920 & 19283+1944 \\
934 & 19352+2030 & 939 & 19374+1626 \\
958 & 19565+3140 & 960 & 19576+2814 \\
966 & 20023+2855 & 972 & 20043+2653 \\
983 & 20137+2838 & 999  & 20272+3535 \\
\hline
\end{tabular}  
\end{table}